Mr Obama prevailed despite lingering dissatisfaction with the economy and a hard-fought challenge by Mr Romney.
BBC: President Barack Obama defeats Romney to win re-election
Facebook is trying to address this challenge by improving the way ads are targeted to users.
Airlines have learned how to cope with the challenge by being obsessed with maintaining public safety.
Planning permission was granted at first, only to be overturned following a legal challenge by other traders.
It is the second legal challenge by law firm Public Interest Lawyers, which is representing the Iraqis.
But a seemingly innocuous challenge by Jorge Andrade proved to be more serious than at first sight.
Earlier this month, he was re-elected ANC leader, beating off a challenge by his rival, Kgalema Motlanthe.
Messi escaped the attentions of Arjen Robben, but was halted by a clumsy challenge by Chelsea's Spanish defender.
Poll then blocked an attempted challenge by Michael Tonge as Arsenal broke forward.
Introduction of the measure had been delayed because of a legal challenge by manufacturer Imperial Tobacco, which was defeated.
The latest deal has been signed despite a fresh challenge by Leyton Orient.
It hopes to avoid a legal challenge by restricting the number of people with whom users can swap files.
The Pacers answered the second challenge by converting back-to-back turnovers into four points.
Teams rise to the challenge by decorating their commodes to look like everything from a jail to a toxic waste dumping facility.
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Incumbent Prime Minister Tillman Thomas (National Democratic Congress) is facing a challenge by veteran New National Party leader Keith Mitchell.
Mr Turner said he thought the decision to close the factory could be subject to a legal challenge by unions.
BBC: Seven Seas to close Hull factory with up to 250 job losses
Staff at the Home Office and UK Border Agency did not join the stoppage following a legal challenge by the government.
Sweden has suspended a controversial cull of its wolf population shortly after it began because of a legal challenge by conservationists.
But a high challenge by James on Max Evans gave sub Ruaridh Jackson the penalty to edge the home side in front.
His remarks came a week after a federal appeals court said Aereo could continue its service despite a legal challenge by broadcasters.
Boeheim answered the challenge by guiding the Orange to a school-record 34 wins, just missing his fourth berth in the Final Four.
There was another injury blow for Kilmarnock when Dayton had to be replaced with James Fowler following a challenge by Jure Travner.
He refused to meet a challenge by pro-Europeans led by Tory Michael Heseltine to head up the all-party Britain in Europe campaign.
Hillary's campaign is even gearing up for a potential challenge by Gore.
Concerns about security regarding the use of social media are seen as a top challenge by the largest number of respondents (41%).
FORBES: Social Media Risk Is Like Wildfire. Where's the Fire Engine?
The latter looked like just getting there but Bust Out gave a little bit more to hole off the challenge by a length.
Finnigan won a penalty for his side following a challenge by Esson, who was promptly shown a red card by referee Calum Murray.
Universities and business schools in the region are responding to the challenge by extending their offerings in open and customized executive education courses.
Ole Gunnar Solskjaer's match and season came to an abrupt halt after a late challenge by Ugo Ehiogu, and he was replaced by Jordi Cruyff.
World No. 2 Rory McIlroy, like Woods favored for eventual victory, sustained his challenge by finishing with two birdies to card a challenging 71.
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